A variety of input devices may be used to provide position and control data to programs executing on computers, cell phones, and other processor-equipped devices. These input devices include mice, trackballs, touchpads, touch screens, touch panels, and various other devices. While the mouse and trackball provide distinct control elements for performing positioning and other control actions, the touchpad combines positioning and control.
For example, a conventional mouse includes a ball or optical sensor for determining changes in position of the mouse. The mouse also includes one or more buttons for performing a control function, such as selecting a graphical representation on a screen. In these systems, a user's intent to make a positional change or provide control input is apparent to the system.
In contrast, conventional touchpads combine the position and control functionality in a way that often masks the user's intent to make a positional change to provide control input. A user moves a finger along a touchpad to reposition a cursor. A user may also perform gestures to simulate functions of the buttons of a mouse, such as drag, click, and double-click. In either case, the user's finger is in contact with the surface of the touchpad. Changes in position on the touchpad and in the pressure exerted on the surface of the touchpad must be used to determine the user's intent. Because of the variety of users that may interact with a touchpad and the variety of functions that may be performed, determining the user's intent based on a gesture on a touchpad is difficult. Variables affecting the ability of a program to determine what a user is attempting to do include the following: the physical difference between users; the different angles at which a user may place their finger while using a touchpad; the variance in pressure between different users and between the same user; the movement of the finger across the touchpad while simultaneously attempting to perform actions on the touchpad. U.S. Pat. No. 6,414,671 to Gillespie, et al. describes one conventional method for recognizing a user's gesture as a drag gesture.
Thus, a method and system are needed for accurately determining a user's intent based on data supplied by a touch-sensitive input device.